The present invention relates generally to brake assemblies for automotive vehicles. More particularly, the invention relates to brake pad assemblies for drum brakes and to an improved brake shoe assembly for drum brakes such as those used on buses and trucks.
In the past, brake shoes for buses and trucks had to be removed from the bus or truck and rebonded with an asbestos material or similar material in order to repair or replace a used brake pad. The entire brake shoe had to be removed from the brake assembly and sent to a bonding facility for repair. An inventory of entire brake shoes had to be maintained by a repair facility in order to keep buses and/or trucks in service. The brake shoes for the buses and trucks are relatively heavy parts and inventories of these large, heavy parts are fairly expensive to maintain due to the cost of the extra parts themselves, the space needed to inventory the parts, and the curbersome nature of the entire brake shoe.
One embodiment of the present invention includes a practical and replaceable brake pad for the brake shoes of buses or trucks. The replaceable brake pad eliminates the need to have a substantial inventory of actual brake shoes and permits a repair facility to have a such lighter weight, less cumbersome, less expensive inventory of merely the pad element of the shoes alone, which pad elements also take up much less space than an inventory of the entire brake shoes.
This embodiment of the present invention may also permit multiple types of brake pads on the same shoes. Different friction characteristics of pads may be desirable on buses or similar vehicles to reduce noise and equalize wear on brake pads. It is commonly known to use medium friction blocks on reverse shoes and low friction blocks on forward shoes in each brake of a bus or to use medium friction blocks on front axial shoes and low friction blocks on rear axial shoes to balance the braking effort of bus. With this embodiment of the present invention, upper and lower friction blocks on the same shoe may be altered to further vary friction characteristics to modify noise or braking effort as desired by a particular installation on a bus or truck. The above objects are all provided in one device that is easy to manufacture, less costly to manufacture and also less costly to buy and less costly to inventory.
Another embodiment of the present invention includes an improved brake shoe assembly having fastening means for attaching the brake pad assembly to the brake shoe that enables the fastening force to be set and controlled automatically for properly securing the brake pad assembly to the brake shoe. The fastening means further provides both an audio and a visual indication when a predetermined level of fastening force has been reached so that the pad assembly can be secured to the brake shoe without over-tightening or under-tightening the assembly and its constituent parts.
Additional objects and advantages of the present invention will be seen in the following claims, description of the drawings and additional specification.